Aerosol dispensing containers have found widespread use in the packaging of fluid materials including a variety of both liquid and powdered particulate products. Such containers are provided with a valve-controlled discharge orifice and operate by the action of a volatile propellant which is confined within the container together with the product to be dispensed. Because the propellant has an appreciable vapor pressure at room temperature, the product in the closed container is maintained under super-atmospheric pressure.
A typical aerosol unit comprises a hollow cylindrical container which is tightly closed at one end and is provided with an opening at its opposite end for receiving a dispensing valve assembly. A closure, commonly referred to as a mounting cup, serves as the closure for the container and as a support for the valve assembly. Typically, the mounting cup comprises a panel having an aperture for receiving the valve assembly, a skirt depending from the periphery of the panel, and an annular channel extending outwardly from the edge of the skirt. When the mounting cup is placed in sealing position on the container, the channel is positioned over the bead surrounding the container opening and the lower portion of the skirt adjacent to the channel is flared outwardly against the container wall adjacent the bead. To ensure adequate sealing between the closure and the container, the cup is provided with a gasket which may reside in the annular channel or predominantly in the channel of the cup.
Heretofore, mounting cup gasket seals have been formed by disposing a previously cut gasket in the channel. This type of gasket has the disadvantage of not being stationary relative to the mounting cup during propellant filling or other valve unit assembly operations with the undesirable consequence that when the mounting cup and container are clinched to effect the seal, the gasket is often disposed at an angled position, and thus, the clinching operation is less effective.
Another commercial method for forming the gasket onto the mounting cup consists in forming the gaskets, in situ, from liquid gasket-forming compositions comprising an elastomer dispersed or dissolved in a volatile organic liquid vehicle. In the manufacture of such a gasket, the liquid composition is deposited in the desired configuration in the channel of the cup while the cup is rotated beneath a metering nozzle through which the composition flows. The deposit is then converted into a dry solid sealing mass by expelling the liquid vehicle at elevated temperatures. Though this technique of flowing gaskets into place has received wide commercial acceptance, it suffers from the disadvantages of requiring an elaborate drying operation, wherein the mounting cup must be handled carefully so as to avoid undue upset from the horizontal; costly recovery apparatus for the expelled organic liquid also must be provided. In sum, the flowed gasket is an expensive step in the formation of the mounting cup. See U.S. Pat. No. 3,342,381 as an example of the "flowed" gasket.
Other techniques for disposing a gasket onto the mounting cup are described in U.S. Pat. No. 3,417,177, wherein the gasket seal is made of heat shrinkable material. After placing a band of gasket material on the skirt, the gasket having a greater diameter than the outside diameter of the skirt of the mounting cup, the cup is heated at a temperature and for a time sufficient to shrink the band into tight frictional engagement with the skirt.
Another similar technique is that disclosed in U.S. Pat. No. 3,443,006, wherein a band of gasket material is swelled through the use of a suitable swelling agent so as to increase its diameter to fit over the skirt of the mounting cup. Subsequently, the swelling agent is removed from the gasket material so that the band will come into tight frictional engagement with the skirt.
Both the heat shrink and swelling techniques for applying a gasket material to the mounting cup have the disadvantage of being costly and relatively time consuming procedures. Note in U.S. Pat. No. 3,417,177, column 4, lines 27-31, that the positioned bands must be heated to 240.degree. F. for about 2-3 minutes in order to obtain a tight friction fit. In the procedure of U.S. Pat. No. 3,443,006, the bands must stand in the swelling liquid for a period of 1/2 to 1-1/2 minutes according to example 2 of the '006 patent and then allowed to stand for the drying period. Also, in any mass production utilizing the '006 system, an organic liquid recovery system must be employed.
In the United States Patent Application Ser. No. 112,791, filed Feb. 1, 1980, is described a novel gasketed mounting cup system, including novel method and apparatus, wherein the gasket material is disposed on the mounting cup in the preferred position for effecting a seal between the mounting cup and the bead of the container; and further wherein the disadvantages associated with the aforementioned techniques of applying the gasket material to the cup are obviated. Also, an apparatus and method is provided wherein gaskets are applied to aerosol mounting cups in an exceptionally rapid and efficient manner to form gasketed-mounting cups having excellent sealing characteristics.
In general, the method of the invention of the aforesaid U.S. Ser. No. 112,791 comprises passing a tubular sleeve of gasket material onto a compressible mandrel; initially positioning and aligning the skirt of the mounting cup and the contiguous end of the mandrel such that the sleeve of gasket material may pass onto the skirt, said mandrel having fixed and moveable portions with respect to each other and to their movement toward and away from the mounting cup; urging the moveable portion of the gasket material bearing mandrel toward the mounting cup such that the gasket material passes onto the skirt of the cup; causing the moveable portion of the mandrel to retract to its initial position, cutting the sleeve at a point between the mounting cup and the mandrel to leave a band of gasket material; and subsequently, advancing the mounting cup to a station whereat the band of the gasket material is urged further onto the skirt of the mounting cup, whereby, the band of gasket material does not extend beyond the skirt of the mounting cup. At this stage, the gasketed-mounting cup may be further processed.
For certain applications of the gasketed mounting cups of Ser. No. 112,791, namely, utilizing said mounting cups in so-called "under the cup" propellant filling of the container, it was observed that on limited occasions the gasket band was removed from the mounting cup during the filling operation Moreover, observation revealed a tendency in an untoward number of gasketed mounting cups for the band of gasket material to recede from its position in the channel or curl portion of the mounting cup before crimping the mounting cup to the container. Both of these disadvantages reduce productivity on a mass production basis.
The subject invention is an improvement in the method and apparatus utilized in the aforesaid Ser. No. 112,791 and the cup produced thereby.
In general, the product of the subject invention comprises disposing one or more compressive deformations in the band of gasket material.
The present invention will be more clearly understood by referring to the drawings herein and the discussion relating thereto.